Not TX300mag, but this is what I think is the most simple way to cook shanks for a beginner.
Brown shanks in a dutch oven. Then remove.
Quarter an onion, chunk up 2 carrots and 2 celery stalks. Then brown in dutch oven.
Set shank back in dutch oven with the vegetables. Pour in any shank juices that came out of it.
Pour in cheap, store bought, chicken broth to within 1" of the top of the shank. Don't use the good homemade stuff, because this cheap stuff will taste amazing once done.
Throw in 3 or 4 sprigs of thyme.
Cover and simmer for 3-4 hours. The meat will slowly pull back from the bone as the connective tissue breaks down. You'll know when it's done when the meat crumbles/shreds when you pinch it with tongs. It would be really hard to over cook it, but if it still gives you some resistance when you try to break it up, it's not done.
After you cook a couple this way, there's a million different things you can could it with for different results. But, you just have to make sure you cook it long enough.